In 2017 alone, five Kenyans have been killed by the militants over accusations of working with Kenya Defence Force (KDF) and the Somali government.

According to the Standard, foreign fighters detained as spies are tortured by water-boarding, beating as well as food and sleep deprivation.

''One of the alleged fighter spies was recently tied to the back of an SUV and driven around town for the locals to witness what would happen to them if they spied on the group,'' the Standard reported.

The execution of foreign fighters has been linked to a power struggle within the terror group as local militants fear losing command of the group to the outsiders.

Al-Shabaab emerged in 2006 from the now-defunct Islamic Courts Union, which once controlled Somalia’s capital of Mogadishu.

The militant group launched its own insurgency on major Somali cities in 2009, taking control of Mogadishu and southern Somalia. In 2015, the militant group launched a deadly assault on Garissa University College.

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